A brushless motor with a built-in position sensor and a built-in drive-control circuit is disclosed in, e.g. Patent Literature 1, as a brushless motor with a built-in circuit board. This conventional brushless motor comprises the following structural elements:                a hermetic cylindrical motor housing;        a rotor having a drive magnet and accommodated in the housing;        a stator core wound with a drive wiring and disposed around an outer circumference of the rotor, and accommodated in and fixed to the motor housing;        a positioning section protruding from an end face of the stator core along an axial direction; and        a circuit board mounted with a position sensor that senses a rotor position, and disposed at the positioning section such that the circuit board is positioned along the axial direction and a circumferential direction.        
The foregoing structure allows the brushless motor to perform a reliable positioning.
Another brushless motor with a built-in circuit board and lead-wires extending to the outside is disclosed in, e.g. Patent Literature 2. This conventional brushless motor comprises the following structural elements:                a motor housing formed of a first component a part of which has a notch, and a second component covering an opening of the notch; and        a split grommet for sandwiching the lead-wires.        
A first slip of the split grommet sandwiching the lead-wire is engaged with the notch, and a second slip of the split grommet is nipped between the notch and the second component in order to prevent the second slip from dropping. The foregoing structure allows the lead-wires to extend to the outside with ease and allows preventing the lead-wires from being cut by failure.
In the case of the brushless motor disclosed in Patent Literature 1, the circuit board should be held and inserted into the motor housing before the circuit board is fixed to the housing. The workability is thus obliged to lower. For instance, in the case of fixing the circuit board manually inside the housing, a worker who holds the board by hand needs to put his or her hand into the motor housing; however, since an inner diameter of the motor housing is nearly equal to an outer diameter of the circuit board, it is difficult to place the circuit board at the positioning section.
On the other hand, the brushless motor disclosed in Patent Literature 2 has a notch on the motor housing, so that a part of the circuit board can be protruded from this notch, whereby the circuit board can be inserted into the motor housing with the protruding section held. However, since the circuit board protrudes in part from the motor housing, the brushless motor is obliged to be greater in size.
In the case of the brushless motor including a circuit board mounted with a position sensor, when the circuit board is misaligned with respect to the stator, an energizing timing to the stator windings is off in response to this misalignment. This timing-off sometimes varies the energizing timing of individual motors manufactured, which causes dispersion in motor characteristics. A rotating efficiency of the motor lowers depending on a magnitude of the timing-off, and the noises increase. On top of that, in the case of the brushless motor, of which circuit board mounted with a position sensor is sealed in the motor housing, the misalignment cannot be simply corrected because the board is enclosed in the motor housing. The circuit board thus needs to be accurately mounted in the motor housing of such brushless motors as discussed above.
Patent Literature 1: Unexamined Japanese Patent Application Publication No. 2005-341780
Patent Literature 2: Unexamined Japanese Patent Application Publication No. 2009-278801